Asthma

The exact cause of asthma is unknown, and the causes may vary from person to person. However, asthma is often the result of a strong response of the immune system to a substance in the lungs. To understand asthma, it helps to understand How the Lungs Work.

Normally, the body’s immune system helps to fight infections. Sometimes a person’s immune system responds to a substance in the environment called an allergen. When someone breathes in an allergen, such as ragweed, the immune system in the airways may react strongly. Other people exposed to the same substance may not react at all.

The immune system reacts to an allergen by creating inflammation. Inflammation makes your airways swell and narrow and possibly produce more mucus. This can make it harder to breathe. The muscles around the airways may also tighten, which is called a bronchospasm. This can make it even harder to breathe.

Over time, the airway walls can become thicker. The image below shows how airways narrow during asthma.

Your asthma may have been caused partly by a viral infection or allergens in the air when you were a baby or young child. During this stage of life, your immune system is still developing.

It’s not clear why one person reacts to an exposure while others do not. Genes seem to play a role in making some people more susceptible to asthma.

Your environment or occupation, your family history or genes, other medical conditions, your race or ethnicity, or your sex may raise your risk for developing asthma.

Asthma affects people of all ages, but it often starts during childhood. Sometimes asthma develops in adults, particularly women. This type of asthma is called adult-onset or late-onset asthma.

Environment or occupation

Things in your environment, including at work or home, may raise your risk of developing asthma or make asthma symptoms worse.

• Exposure to cigarette smoke in the womb or in a child’s first few years raises the risk of developing asthma symptoms early in life. This exposure may also affect lung growth and development.
• Exposure to different microbes in the environment, especially early in life, can affect how the immune system develops. These effects on the immune system may either increase or protect against the risk of developing asthma.
• Exposures that occur in the workplace, such as chemical irritants or industrial dusts, may also raise the risk of developing asthma in susceptible people. This type of asthma is called occupational asthma. It may develop over a period of years, and it often lasts even after you are no longer exposed.
• Poor air quality from pollution or allergens may make asthma worse. Pollutants may include traffic-related air pollution. Allergens in the air may include pollen, dust, or other particles.

Family history and genes

Genes may play a role in the development of asthma because they affect how the immune system develops. More than one gene is likely involved. You inherit genes from your parents. Having a parent who has asthma, especially if the mother has asthma, increases the risk that a child will develop asthma.

Other medical conditions

Asthma is often linked to other medical conditions, such as:

• Allergies. Asthma is usually a type of allergic reaction. People who have asthma often have other types of allergies. They may have food allergies or get a runny or stuffy nose from pollen. You may be at higher risk for developing asthma if you had allergic reactions in early childhood to substances in the air, such as pollen, dander, mold, or dust. The more things you are allergic to, the higher your risk of asthma.
• Obesity can increase the chances of developing asthma or worsening asthma symptoms. This may be because people who have obesity can have inflammation or changes in the immune system.
• Respiratory infections and wheezing. Young children who often have respiratory infections caused by viruses are at highest risk of developing asthma symptoms early in life.

Race or ethnicity

African Americans and Puerto Ricans are at higher risk of asthma than people of other races or ethnicities. African American and Hispanic children are more likely to die from asthma-related causes than non-Hispanic white Americans.

Sex

Among children, more boys than girls have asthma. Among teens and adults, asthma is more common among women than men.

There is no routine screening for asthma, and there is no way to prevent asthma. Your doctor may recommend avoiding certain risk factors to help prevent asthma from getting worse or causing asthma attacks.

Learn about tests your doctor may use to diagnose asthma.

How often signs and symptoms of asthma occur may depend on how severe, or intense, the asthma is and whether you are exposed to allergens. Some people have symptoms every day, while others have symptoms only a few days of the year. For some people, asthma may cause discomfort but does not interfere with daily activities. If you have more severe asthma, however, your asthma may limit what you are able to do.

When asthma is well controlled, a person shows few symptoms. When symptoms worsen, a person can have what is called an asthma attack, or an exacerbation. Over time, uncontrolled asthma can damage the airways in the lungs.

Signs and symptoms

Signs and symptoms of asthma may include:

• Chest tightness
• Coughing, especially at night or early morning
• Shortness of breath
• Wheezing, which causes a whistling sound when you exhale

While other conditions can cause the same symptoms as asthma, the pattern of symptoms in people who have asthma usually has some of the following characteristics.

• They come and go over time or within the same day.
• They start or get worse with viral infections, such as a cold.
• They are triggered by exercise, allergies, cold air, or hyperventilation from laughing or crying.
• They are worse at night or in the morning

Asthma attacks, or exacerbations, are episodes that occur when symptoms get much worse and require a change in typical treatment. These can come on gradually or suddenly and may be life-threatening. People who have severe asthma often get asthma attacks more often.

Asthma is diagnosed based on your medical history, a physical exam, and results from diagnostic tests. You may need to see a team of healthcare providers, including your doctor; an asthma specialist, called a pulmonologist; or an allergy specialist, called an allergist.

Medical history and physical exam

Your doctor will ask about your risk factors for asthma and your symptoms. They may ask also about any known allergies. This includes how often symptoms occur, what seems to trigger your symptoms, when or where symptoms occur, and if your symptoms wake you up at night.

During the physical exam, your doctor may:

• Listen to your breathing and look for symptoms of asthma
• Look for allergic skin conditions, such as eczema

Diagnostic tests

Your doctor may ask you to perform the following tests to determine whether your symptoms are caused by asthma.

• Pulmonary function tests, such as spirometry, which involves breathing in and out through a tube connected to a computer. This measures how much and how fast the air moves when you breathe in and out with maximum effort. Watch this video to learn more about taking a spirometry test.
• Spirometry with bronchodilator tests to measure how much and how fast air moves in and out both before and after you take an inhaled medicine to relax the muscles in your airway.
• Bronchoprovocation tests to measure how your airways react to specific exposures. During this test, you inhale different concentrations of allergens or medicines that may tighten the muscles in your airways. Spirometry is done before and after the test.
• Peak expiratory flow (PEF) tests to measure how fast you can blow air out using maximum effort. This test can be done during spirometry or by breathing into a separate device, such as a tube.
• Fractional exhaled nitric oxide (FeNO) tests to measure levels of nitric oxide in your breath when you breathe out. High levels of nitric oxide may mean that your lungs are inflamed. This test is done in adults and children age 5 and older. Read the FeNO fact sheet to learn more.
• Allergy skin or blood tests, if you have a history of allergies. These tests can tell your doctor which allergens, such as pet dander or pollen, causes a reaction from your immune system.

Diagnosing asthma in children younger than 6

It can be hard to tell whether a child under age 6 has asthma or another respiratory condition, because young children often cannot perform a pulmonary function test such as spirometry. After checking a child’s history and symptoms, the doctor may try asthma medicines for a few months to see how well a child responds. About 40% of children who wheeze when they get colds or respiratory infections are eventually diagnosed with asthma.

If you are diagnosed with asthma, your doctor will work with you to create a treatment plan to manage your asthma symptoms and prevent asthma attacks. Treatment usually depends on your age, asthma severity, and response to a given treatment option. Your doctor may adjust your treatment until asthma symptoms are controlled.

Most people are treated long-term with daily controller(s), along with another inhaler for short-term relief, when they have symptoms or to prevent symptoms. An inhaler allows the medicine to go into the mouth and airways.

Watch our video to learn about treatment for asthma. 

Short-term relief medicines

Short-term relief medicines, also called quick-relief medicines, help prevent symptoms or relieve symptoms during an asthma attack. They may be the only medicines needed for mild asthma or asthma that happens only with physical activity.

Your doctor will prescribe a quick-relief inhaler for you to carry at all times. Visit the Centers for Disease Control and Prevention (CDC) to learn how to use your asthma inhaler correctly.

Types of short-term relief medicines include:

• Inhaled short-acting beta2-agonists (SABAs) to quickly relax tight muscles around your airways. This allows the airways to open so air can flow through them. Side effects can include tremors and rapid heartbeat. If symptoms and medical history suggest asthma, doctors may treat it with inhaled corticosteroids for a trial period to see whether they help. If symptoms do not improve, corticosteroids will be stopped to avoid side effects.
• Oral and intravenous (IV) corticosteroids to reduce inflammation caused by severe asthma symptoms.
• Short-acting anticholinergics to help open the airways quickly. This medicine may be less effective than SABAs, but it is an option for people who may have side effects from SABAs.

Control medicines

Your doctor may prescribe long-term control medicines to take daily to help prevent symptoms by reducing airway inflammation and preventing narrowing of the airways. Treatment with specific control medicines may differ depending on age, such as whether the person is an adult or child. Return to Causes to review what causes asthma symptoms.

Control medicines include the following.

• Corticosteroids to reduce the body’s inflammatory response. Your doctor may prescribe inhaled or oral (as a pill) corticosteroids. Common side effects from inhaled corticosteroids include a hoarse voice or a mouth infection called thrush. A spacer or holding chamber on your inhaler can help avoid these side effects. Oral corticosteroids can have more side effects than inhaled corticosteroids, because the medicine goes outside the lungs. Read more about inhaled corticosteroids for asthma management. Read more about inhaled corticosteroids for asthma management.
• Biologic medicines, such as omalizumab, mepolizumab, reslizumab, and benralizumab, to target specific parts of the body’s response to allergens. Biologic medicines are antibodies used in people who have severe asthma. Benralizumab is injected into a vein, while the other medicines are injected below the skin or in a vein. They are given every few weeks.
• Leukotriene modifiers to reduce inflammation and keep your airways open. You take these pills by mouth, alone or with corticosteroids, depending on what your doctor prescribes.
• Mast cell stabilizers, such as cromolyn, to help prevent airway inflammation when you are exposed to allergens or other triggers. These medicines stop certain immune cells from releasing the signals that cause inflammation.
• Inhaled long-acting bronchodilators, such as long-acting beta2-agonists (LABAs), to keep the airways open by preventing narrowing of the airways. LABAs may be added to your inhaled corticosteroids to reduce narrowing and inflammation. A similar medicine called inhaled long-acting muscarinic antagonists (LAMAs) is sometimes also used. Read more about LAMAs in our fact sheet.
• Immunotherapy to reduce the body’s response to allergens. It can be given as an injection, known as an allergy shot, or by mouth as a liquid or tablet. Read more about immunotherapy in our fact sheet.

Emergency care

If you have a severe asthma attack and need emergency care, you may be treated with medicines, such as those listed above, given with a nebulizer or IV. You may also receive oxygen therapy or breathing assistance. This may include ventilator support or through a mask with forced air.

Procedures

In certain cases, your doctor may recommend a procedure called bronchial thermoplasty if you are 18 years or older and have severe asthma that remains uncontrolled despite using other treatments. In this procedure, your doctor will insert a bronchoscope into your airway through the mouth or the nose. This helps your doctor see inside the airways. Heat is used to reduce the muscle around the airway to help prevent constriction. Read more about bronchial thermoplasty in our fact sheet.

After being diagnosed with asthma, work with your doctor to learn how to manage it yourself. Because asthma symptoms may be different at different times, it is important to know which medicines to use to prevent and relieve symptoms. You can work with your doctor to develop a treatment plan, called an asthma action plan. Follow-up care will help to make sure your or your child’s asthma is well-controlled. Staying healthy also includes avoiding asthma triggers and maintaining a healthy lifestyle.

Watch NHLBI’s video Living with and Managing Asthma for more information.

Follow your asthma action plan

Work with your doctor to create an asthma action plan that works for you. An asthma action plan is a written treatment plan document that describes the following.

• How to identify allergens or irritants to avoid
• How to recognize and handle asthma attacks
• Which medicines to take and when to take them
• When to call your doctor or go to the emergency room
• Who to contact in an emergency

If your child has asthma, then your child’s caretakers and school staff should know about the asthma action plan. For a sample plan, see the National Heart, Lung, and Blood Institute’s (NHLBI) Asthma Action Plan.

Your doctor will make sure you are using your inhaler correctly. There are different types of inhalers. Review the way you use your inhaler at every medical visit. Sometimes asthma may get worse because of incorrect inhaler use.

Watch our video on Asthma Action Plans to learn more. Then, download a sample Asthma Action Plan.

Know your asthma triggers

Asthma triggers are things that set off or worsen asthma symptoms. If you know that your asthma symptoms occur when you are exposed to specific triggers, it may be worthwhile to reduce your exposure to those triggers, using multiple different methods to reduce the exposure.

Allergens are a common trigger for asthma.

• If you are sensitive to dust, consider removing carpet from your home and using air purifiers and mattress and pillowcases that keep out dust mites.
• If you are sensitive to mice or cockroaches, consider using multiple ways of removing them or preventing them from entering the home in the first place.

Other asthma triggers include:

• Emotional stress. Emotional stress, such as intense anger, crying, or laughing, can cause hyperventilation and airway narrowing, triggering an asthma attack.
• Infections, such as influenza (flu). Get the flu vaccine each year to help prevent the flu, which can raise the risk of an asthma attack.
• Medicines. Some people who have severe asthma may be sensitive to medicines, such as aspirin, and may experience serious respiratory problems. Tell your doctor about all medicines you or your child currently takes.
• Poor air quality or very cold air. Pollution or certain kinds of weather, such as thunderstorms, can affect air quality. Pollution can include indoor pollution caused by gases from inefficient cooking or heating devices that are not vented. Outdoor air pollution may be hard to avoid, but you can keep windows closed and avoid strenuous outdoor activity when air quality is low. For guidance, check the National Oceanic and Atmospheric Administration’s Air Quality Forecast Guidance.
• Tobacco smoke, including secondhand smoke.
• Certain foods or food additives (chemicals). This is less common.

Read more about reducing allergens in your home.

Receive routine medical care

Regular checkups are important to help your doctor determine how well you are controlling your asthma and adjust treatment if needed. Your doctor will also do regular tests to see how well your lungs are working and how well air is flowing.

Your medicines or dosages may change over time, based on changes in your condition or in your life, such as:

• Age. Older adults may need different treatments because of other conditions they may have and medicines they may take. Beta-blockers, pain relievers, and anti-inflammatory medicines can affect asthma.
• Pregnancy. Your asthma symptoms may change during pregnancy. You are also at higher risk of asthma attacks. Your doctor will continue to treat you with long-term medicines such as inhaled corticosteroids. Controlling your asthma is important for preventing complications such as preeclampsia, pre-term delivery, and low birth weight of the baby.
• Surgery. Asthma may increase your risk of complications during and after surgery. For instance, having a tube put into your throat may cause an asthma attack. Talk to your doctor and surgeon about how to prepare for surgery.

Return to Treatment to review possible treatment options for your asthma.

Manage your asthma at home

Ask your doctor about asthma training or support groups to help you keep asthma under control. Education can help you understand the purpose of your medicines, how to prevent symptoms, how to recognize asthma attacks early, and when to seek medical attention.

As part of your asthma action plan, your doctor may show you how to monitor your asthma using a peak flow meter. You can compare your numbers over time to make sure your asthma is controlled. A low number can help warn you of an asthma attack, even before you notice symptoms.

Keeping a diary may help if you find it hard to follow your asthma action plan or the plan is not working well. If you have any of the following experiences, record them in the diary and make an appointment to see your doctor. Bring the diary with you to your appointment.

• You are limiting normal activities and missing school or work.
• You use your quick-relief inhaler more than two days a week.
• Your asthma medicines do not seem to work well anymore.
• Your peak flow number is low or varies a lot from day to day.
• Your symptoms occur more often, are more severe, or cause you to lose sleep.

If your young child’s asthma is not well-controlled, you may notice that he or she is coughing more at night and eating less. Your child also may seem more tired (called fatigue), irritable, or moody.

Make healthy lifestyle changes

Your doctor may recommend one or more of the following heart-healthy lifestyle changes to help keep asthma symptoms in check.

• Aim for a healthy weight. Obesity can make asthma harder to manage. Talk to your doctor about programs that can help. Even a 5% to 10% weight loss can help symptoms.
• Choose heart-healthy foods. Eating more fruits and vegetables and getting enough vitamin D can provide important health benefits.
• Get regular physical activity. Even though exercise is an asthma trigger for some people, you should not avoid it. Physical activity is an important part of a healthy lifestyle. Talk with your doctor about what level of physical activity is right for you. Ask about medicines that can help you stay active.
• Manage stress. Learn breathing and relaxation techniques, which can help symptoms. Meet with a mental health professional if you have anxiety, depression, or panic attacks.
• Quit smoking or avoid secondhand smoke. Smoking tobacco and inhaling smoke from secondhand smoke make asthma harder to treat. Vaping e-cigarettes and getting exposed to secondhand vapor may also be linked to asthma symptoms. Research suggests that nicotine and flavorings found in vaping e-cigarettes can damage your lungs. Visit Smoking and Your Heart or call the National Cancer Institute’s Smoking Quitline at 1-877-44U-QUIT (1-877-448-7848).
• Try to get good quality sleep. Getting quality sleep can sometimes be difficult with asthma. Develop healthy sleep habits by going to sleep and getting up at regular times, following a calming bedtime routine, and keeping you bedroom cool and dark. 

Prevent complications from asthma

Your doctor may recommend that you keep your medicine dose as low as possible to prevent long-term side effects. High doses of certain asthma medicines over time can increase your risk of cataracts and osteoporosis. A cataract is the clouding of lens in your eye. Osteoporosis is a disorder that makes your bones weak and more likely to break. Read more in What People With Asthma Need To Know About Osteoporosis.

Keep your asthma under control and contact your doctor if anything changes. When asthma is unmanaged, it can lead to potentially life-threatening asthma attacks. If you are pregnant, it can put the health of your unborn baby at risk.

Have a plan for asthma attacks

A written asthma action plan developed with your doctor can help you know when to call 9-1-1 for emergency care.

Asthma attacks can be more dangerous for some people. You should seek care immediately during an asthma attack if you or your child:

• Has been hospitalized for asthma in the past year
• Has had life-threatening asthma attacks in the past
• Recently needed oral corticosteroids
• Has not been using inhaled corticosteroids
• Uses more than one canister of inhaled short-acting beta2-agonists (SABAs) medicine each month
• Has a mental health condition or alcohol or drug use disorder
• Does not closely follow your asthma action plan
• Has a food allergy

For young children with asthma, call 9-1-1 if they:

• Seem drowsy, confused, or agitated
• Have a blue tint to the skin and lips
• Have a fast heartbeat

Call your doctor if:

• Your medicines do not relieve an asthma attack
• Your peak flow number is low